USC to UMP conversion - swapping internals

I am thinking about doing the USC to UMP conversion and have a newbie question, if you don't mind.

If I get the FBI style UMP lower (like this one here on HKParts), I do not have to swap out its internals with the USC internals because it is already S/F (0,1)? Now if I get the Navy style UMP lower, I have to swap out the internals with my USC internals?

Or do I have to swap out the internals regardless of whether FBI or Navy?

The only one I'd suggest staying away from is the burst pack. The selector is configured differently than the USC, FBI, and SEF packs, so moving the parts from one to another requires modifying the internal parts.

The only one I'd suggest staying away from is the burst pack. The selector is configured differently than the USC, FBI, and SEF packs, so moving the parts from one to another requires modifying the internal parts.